Substituted-9H-pyrrolo[3,4-b]quinolin-9-ones and treatment of allergic conditions with them

ABSTRACT

This invention provides compounds of formula ##STR1## wherein R 1  is hydrogen, alkyl, alkenyl or alkynyl, the multiple bond of which is not adjacent to the nitrogen atom, 
     R 2  is, for example, hydrogen, alkyl, alkoxy, hydroxy or halogen, and 
     R 3  is hydrogen, halogen, hydroxyl, alkyl or alkoxy, 
     useful, for example, in the treatment of allergic asthma.

This is a continuation of application Ser. No. 842,200 filed Oct. 14, 1977, now abandoned.

The present invention relates to 1,2,3,4-tetrahydro-9H-pyrrolo[3,4-b]quinolin-9-one derivatives.

More particularly, the present invention provides compounds of formula I, ##STR2## wherein R₁ is hydrogen, alkyl of 1 to 4 carbon atoms, alkenyl or alkynyl, each of 3 to 5 carbon atoms, the multiple bond of which is not adjacent to the nitrogen atom,

R₂ is hydrogen, alkyl or alkoxy, each of 1 to 8 carbon atoms, hydroxyl, fluorine, chlorine, bromine, trifluoromethyl, carboxyl or --NR₄ R₅,

R₃ is hydrogen, fluorine, chlorine, bromine, hydroxyl, alkyl or alkoxy, each of 1 to 8 carbon atoms,

R₄ is hydrogen, alkyl of 1 to 4 carbon atoms, phenyl or --SO₂ R₆,

R₅ is hydrogen or alkyl of 1 to 4 carbon atoms and

R₆ is alkyl of 1 to 4 carbon atoms, phenyl or phenyl monosubstituted by alkyl or alkoxy, each of 1 to 4 carbon atoms, fluorine, chlorine or bromine.

When R₁ is alkyl, this is preferably methyl. R₁ is preferably hydrogen or methyl. When R₁ is alkenyl of 3 to 5 carbon atoms, this may, for example, be propenyl. R₁ may also be alkynyl of 3 to 5 carbon atoms, for example, butynyl.

R₂ is preferably chlorine or trifluoromethyl. R₂ can also be fluorine or bromine. R₂ may be alkyl of 1 to 8 carbon atoms, suitably of 1 to 6 carbon atoms or of 1 to 3 carbon atoms, for example, methyl, propyl, hexyl or octyl. R₂ may be alkoxy of 1 to 8 carbon atoms, suitably of 1 to 6 carbon atoms or of 1 to 3 carbon atoms, for example, methoxy, propoxy, hexyloxy or octyloxy. In one group of compounds, R₂ is hydroxy. In a second group of compounds, R₂ is carboxyl. When R₂ is --NR₄ R₅, R₄ and R₅ may each be alkyl of 1 to 4 carbon atoms. R₄ may also be phenyl. When R₄ is --SO₂ R₆, R₆ may be alkyl of 1 to 4 carbon atoms. R₆ may also be phenyl or phenyl monosubstituted by alkyl or alkoxy, each of 1 to 4 carbon atoms, fluorine or chlorine.

R₃ is preferably hydrogen. R₃ may be fluorine, chlorine or bromine. In one group of compounds, R₃ is hydroxy. R₃ may be alkyl of 1 to 8 carbon atoms, suitably of 1 to 6 carbon atoms or of 1 to 3 carbon atoms, for example, methyl, propyl, hexyl or octyl. R₃ may be alkoxy of 1 to 8 carbon atoms, suitably of 1 to 6 carbon atoms or of 1 to 3 carbon atoms, for example, methoxy, propoxy, hexyloxy or octyloxy.

In one group of compounds, R₁ is alkyl of 1 to 4 carbon atoms, R₂ is fluorine, chlorine, bromine or trifluoromethyl and R₃ is hydrogen.

The invention further provides a process for the production of a compound of formula I, comprising hydrolysing a compound of formula II, ##STR3## wherein R₁ is as previously defined,

R'₂ is hydrogen, alkyl or alkoxy, each of 1 to 8 carbon atoms, hydroxyl, fluorine, chlorine, bromine, trifluoromethyl, --COOR₇, --OOCR₈ or --NR'₄ R₅,

R'₃ is hydrogen, alkyl or alkoxy, each of 1 to 8 carbon atoms, hydroxyl, fluorine, chlorine, bromine or --OOCR₈,

R'₄ is hydrogen, alkyl of 1 to 4 carbon atoms, phenyl, --SO₂ R₆ or --Z,

R₇ is alkyl of 1 to 4 carbon atoms,

R₈ is hydrogen, alkyl of 1 to 4 carbon atoms, phenyl or p-nitrophenyl,

Z is --CO--Y,

Y is hydrogen, alkyl or alkoxy, each of 1 to 4 carbon atoms, phenyl, p-nitrophenyl or phenoxy,

and R₅ and R₆ are as previously defined.

The conversion of the compounds of formula II to the compounds of formula I can be effected by known methods for the hydrolysis of carboxylic acid amides or carbamates to secondary amines. The hydrolysis can be effected in an acid medium, e.g. with HBr in glacial acetic acid, or in an alkaline medium, e.g. with an alkali hydroxide such as NaOH or KOH or with Ba(OH)₂ in an aqueous alcohol.

The hydrolysis is preferably effected at the reflux temperature of the reaction mixture. The R₈ COO--, --COOR₇ and/or NR₅ Z groups which may be present are simultaneously converted to hydroxyl, free carboxyl or --NHR₅ groups, respectively.

The resulting compounds of formula I may be isolated and purified using conventional techniques.

Free base forms of the compounds of formula I may be converted into acid addition salt forms and vice versa in conventional manner.

The starting materials of formula II may be produced as follows:

(a) Compounds of formula IIa, ##STR4## wherein R'₃ and Z are as previously defined, and

R"₂ has the same significance as R'₂ with the exception of --NH₂,

may, for example, be obtained by cyclisation of compounds of formula III, ##STR5## wherein R'₃, R"₂, R₇ and Z are as previously defined.

The cyclisation can be effected according to known methods (Conrad-Limpach cyclisation) by heating to temperatures of between ca. 220° and ca. 300° in an inert solvent such as diphenyl ether.

The compounds of formula III can be produced by condensing compounds of formula IV, ##STR6## wherein R'₃ and R"₂ are as previously defined, with compounds of formula V, ##STR7## wherein R₇ and Z are as previously defined.

The condensation can be effected according to known methods for the condensation of anilines with β-keto esters, for example, by boiling in CCl₄ or ethanol, optionally in the presence of an acid catalyst such as hydrochloric acid or formic acid or acid salts, e.g. MgSO₄ or CdSO₄.

The compounds of formula IV and V are either known or may be produced by known methods.

(b) Compounds of formula IIb, ##STR8## wherein R'₁ has the same significance as R₁ with the exception of hydrogen,

R"'₂ is hydrogen, alkyl or alkoxy, each of 1 to 8 carbon atoms, fluorine, chlorine, bromine, trifluoromethyl, --COOR₇, --OOCR₈ or --NR"₄ R'₅,

R"₃ is hydrogen, alkyl or alkoxy, each of 1 to 8 carbon atoms, fluorine, chlorine, bromine or --OOCR₈,

R"₄ is alkyl of 1 to 4 carbon atoms, phenyl cr Z,

R'₅ is alkyl of 1 to 4 carbon atoms and

R₇, R₈ and Z are as previously defined,

are produced by alkylating compounds of formula VI, ##STR9## wherein R"'₂, R"₃ and Z are as previously defined.

The N-alkylation can be effected according to known methods, for example, by producing the Na salt with sodium alcoholate in an alcohol and reaction of the salt with an alkyl halide R'₁ X (wherein X is Cl, Br or I) in an inert solvent such as dimethyl formamide or hexamethyl phosphoric triamide or by adding sodium hydride to the base of formula VI and subsequently R'₁ X in a solvent such as dimethyl formamide or hexamethyl phosphoric triamide.

(c) Compounds of formula IIc, ##STR10## wherein R₁ and Z are as previously defined and

R₂ ^(IV) is hydrogen, alkyl of 1 to 8 carbon atoms, hydroxyl, fluorine, chlorine, bromine, trifluoromethyl, --COOR₇, --OOCR₈ or --NR'₄ R₅,

can be obtained by subjecting a compound of formula VII, ##STR11## wherein R₁, R'₂ and Z are as previously defined and

R₉ is alkyl of 1 to 4 carbon atoms or benzyl,

to ether splitting.

The ether splitting can be effected according to known methods, for example, with Lewis acids, such as BBr₃ or BCl₃, in an inert solvent such as methylene chloride, at temperatures of approximately -30° C. to room temperature.

(d) Compounds of formula IId, ##STR12## wherein R₁, R'₃ and Z are as previously defined, can, for example, be prepared by reducing the nitro group in a compound of formula VIII, ##STR13## wherein R₁, R'₃ and Z are as previously defined, to an amino group.

The reaction can be effected according to known methods for reducing aromatic nitro compounds to their corresponding amino derivatives. For example, the compounds of formula VIII can be treated with reducing agents such as TiCl₃ or SnCl₂ in acidic aqueous solution at temperatures of between room temperature and ca. 60° C. A hydrogenolytic reduction of the nitro group, e.g. with hydrogen in the presence of a catalyst such as Raney nickel or palladium on charcoal in an inert solvent such as ethanol or dimethyl formamide at from room temperature to ca. 50° C., can be used for the production of compounds IId. In this latter case, halogen atoms (R₃) or benzyl groups (R₃) may be split off and alkenyl or alkynyl groups (R₁) may be converted into alkyl groups.

The starting materials of formula VIII can be prepared in manner analogous to processes (a) and (b).

(e) Compounds of formula IIe, ##STR14## wherein R'₁, R"₃, R₆ and Z are as previously defined, can be prepared by acylating a compound of formula IX, ##STR15## wherein R'₁, R"₃ and Z are as previously defined, with a compound of formula X,

    R.sub.6 SO.sub.2 M                                         X

wherein R₆ is as previously defined and M is halogen.

The acylation can be effected according to known methods, for example, in the presence of a base such as pyridine, in an inert solvent such as methylene chloride, or according to a Schotten-Baumann reaction.

Processes (c) and (d) for the production of the starting materials of formula II can also be employed for the production of the final products of formula I. Thus, the compounds of formula VII and VIII, wherein Z signifies hydrogen, may respectively be converted into compounds of formula IIc and IId (Z=H) according to process (c) and (d), respectively.

Insofar as the production of starting materials is not described, these are either known or may be produced in accordance with known processes, or in manner analogous to the processes described herein, or to known processes.

In the following non-limitative Examples, all temperatures are indicated in degrees Celsius.

EXAMPLE 1 1,2,3,4-Tetrahydro-4-methyl-9H-pyrrolo[3,4-b]quinolin-9-one

A mixture of 10 g of 2-benzoyl-1,2,3,4-tetrahydro-4-methyl-9H-pyrrolo[3,4-b]quinolin-9-one, 10 g of potassium hydroxide, 10 ml of water and 100 ml of ethanol is heated at reflux for 17 hours, cooled, diluted with 50 ml each of ether and water and filtered. The recrystallisation of the residue from methanol and ether yields 1,2,3,4-tetrahydro-4-methyl-9H-pyrrolo[3,4-b]quinolin-9-one. M.P. 209°-213° (decomposition).

The 2-benzoyl-1,2,3,4-tetrahydro-4-methyl-9H-pyrrolo[3,4-b]quinolin-9-one used as starting material can be prepared as follows:

(a) 3-Anilino-1-benzoyl-2,5-dihydro-1H-pyrrol-4-carboxylic acid ethyl ester

A mixture of 100 g of 1-benzoyl-3-oxopyrrolidin-4-carboxylic acid ethyl ester, 42 ml of aniline and 23 ml of formic acid in 1.2 liters of ethanol is heated to reflux for 15 hours, concentrated by evaporation and the residue is crystallised from the ether/methylene chloride. 3-Anilino-1-benzoyl-2,5-dihydro-1H-pyrrol-4-carboxylic acid ethyl ester is obtained. M.P. 149°-151°.

(b) 2-Benzoyl-1,2,3,4-tetrahydro-9H-pyrrolo[3,4-b]-quinolin-9-one

50 g of 3-anilino-1-benzoyl-2,5-dihydro-1H-pyrrol-4-carboxylic acid ethyl ester are heated at reflux in 500 ml of diphenyl ether for 1.5 hours, the resulting ethanol being continuously distilled off. Upon cooling, the resulting precipitate is filtered by suction, washed with ether and dried. 2-Benzoyl-1,2,3,4-tetrahydro-9H-pyrrolo[3,4-b]-quinolin-9-one is obtained. M.P. 275°.

(c) 2-Benzoyl-1,2,3,4-tetrahydro-4-methyl-9H-pyrrolo-[3,4-b]quinolin-9-one

14.51 g (50 mmol) of the 2-benzoyl-1,2,3,4-tetrahydro-9H-pyrrolo[3,4-b]quinolin-9-one are dissolved in 50 ml of a 1 N solution of sodium methylate in absolute methanol, the solution concentrated by evaporation, the residue taken up in 150 ml of dimethyl formamide and 3.15 ml of methyl iodide are added. After stirring for 4 hours at room temperature, appoximately 100 ml of water are added to the mixture, filtration is effected and the residue is washed with water and dried. The 2-benzoyl-1,2,3,4-tetrahydro-4-methyl-9H-pyrrolo-[3,4-b]quinolin-9-one used in Example 1 is obtained. M.P. 285° (decomposition).

The following compounds can be prepared in manner analogous to that of Example 1, using appropriate starting materials in approximately equivalent amounts. ##STR16##

    __________________________________________________________________________     Ex.                                                                            No.                                                                               R.sub.1    R.sub.2    R.sub.3                                                                             M.P. (° C.)                               __________________________________________________________________________     2  H          H          H    225°-9°                                                                    (+ 1/2 H.sub.2 O)                      3  H          7-OCH.sub.3                                                                               H    280°                                                                         Decomp.                                                                             (+ 1/2 H.sub.2 O)                      4  CH.sub.3   7-Cl       H    259°-62°                                                              Decomp.                                     5  CH.sub.3   7-OCH.sub.3                                                                               H    166°-8°                                                               Decomp.                                                                             (Hydrogenfumarate)                     6  H          5-CH.sub.3 H    286°-8°                                                               Decomp.                                     7  H          5-F        H    >300°                                                                             (Hydrochloride-hemihydrate)            8  H          7-Cl       H    >300°                                                                             (Hydrochloride)                        9  H          5-CH.sub.3 7-Cl 230°                                                                         Decomp.                                                                             (Hydrochloride)                        10 H          5-CH.sub.3 7-CH.sub.3                                                                          >300°                                                                             (Hydrochloride)                        11 H          5-CH.sub.3 6-CH.sub.3                                                                          >300°                                                                             (Hydrochloride-dihydrate)              12 H          7-C.sub.4 H.sub.9                                                                         H    >300°                                                                             (Hydrochloride-hydrate)                13 H          5-C.sub.3 H.sub.7 O                                                                       H    246°-8°                                                               Decomp.                                                                             (Hydrochloride-hydrate)                14 H          7-C.sub.6 H.sub.13 O                                                                      H    290°-5°                                                               Decomp.                                                                             (Hydrochloride)                        15 H          5-CH.sub.3 O                                                                              8-CH.sub.3 O                                                                        >300°                                                                             (Hydrochloride-hydrate)                16 CH.sub.2CHCH.sub.2                                                                        5-CH.sub. 3                                                                               7-CH.sub.3                                                                          135°-8°                                                               Decomp.                                     17 H          5-CH.sub.3 O                                                                              8-CH.sub.3                                                                          >300°                                                                             (Hydrochloride)                        18 H          6-CF.sub.3 7-Cl >260°                                                                             (Hydrochloride)                        19 C.sub.2 H.sub.5                                                                           H          H    114°-8°                            20 H          5-Cl       7-Cl >300°                                                                             (Hydrochloride)                        21 H          5-CF.sub.3 H    >270°                                                                             (Hydrochloride)                        22 H          7-(CH.sub.3).sub.2 N                                                                      H    224°-30°                                                              Decomp.                                                                             (Dihydrochloride-dihydrate)            23 H          7-OH       H    >300°                                                                             (Hydrate)                              24 CH.sub.3   7-NH.sub.2 H    >300°                                     25 (CH.sub.2).sub.2CCH                                                                       5-C.sub.3 H.sub.7                                                                         7-C.sub.2 H.sub.5                                     26 CH.sub.3   7-Br       5-C.sub.2 H.sub.5 O                                   27 CH.sub.3   5-COOH     H                                                     28 H                                                                                                    5-CH.sub.3                                            29 H                                                                                          ##STR17## 5-CH.sub.3 O                                          30 CH.sub.3   5-C.sub.4 H.sub.9 O                                                                       7-F                                                   31 C.sub.2 H.sub.5                                                                           5-C.sub.7 H.sub.15                                                                        7-Br                                                  32 C.sub.4 H.sub.9                                                                           H          6-OH                                                  33 H                                                                                          ##STR18## 5-C.sub.3 H.sub.7                                     __________________________________________________________________________

The compounds of formula I possess pharmacological activity. In particular, the compounds possess disodium chromoglycate (DSCG)-like activity, and are therefore useful in the treatment and prophylaxis of allergic conditions, such as allergic asthma, exercise-induced asthma and allergic gastro-intestinal disorders, as indicated in the passive cutaneous anaphylaxis (PCA) test in the rat.

The method employed is based on those described by Mota (1), Stotland and Share (2) and Perper et al. (3). Female rats (180-200 g) are sensitized by subcutaneous administration of 1 mg of ovalbumin (Fluka No. 05430) and 200 mg of albumin hydroxide gel (Merck No. 1088), dissolved in 1 ml of 0.9% saline, and intraperitoneal administration of 0.5 ml of Haemophilus pertussis vaccine (Schweizerisches Serum- and Impfinstitut, Bern, No. 115,325; 4×10.sup. organism/ml). Fourteen days later, the animals are exsanguinated, the blood centrifuged and the serum (anti-serum) collected and deep frozen.

The anti-serum is injected intradermally (0.1 ml of a 1:100 to 1:200 dilution per injection site) at three sites on the backs of untreated, female rats. Twenty-four hours later (intravenous testing) or forty-eight hours later (oral testing), the rats receive either solvent or the test compound (2 ml/kg i.v. 0.1 to 3.2 mg/kg i.v. or 5 ml/kg p.o. 1 to 32 mg/kg p.o.) followed one minute (intravenous testing), or 7.5 or 15 minutes (oral testing) later by the intradermal injection of histamine (8 μg in 0.05 ml of 0.9% saline) and serotonin (0.5 μg in 0.05 ml of 0.9% saline) at two further sites. Immediately afterwards, the animals receive an intravenous injection of 1 ml of a 0.9% saline solution containing 5 mg of ovalbumin (twice crystallised) and 2.5 mg of Evans blue dye. The ovalbumin, histamine and serotonin elicit a cutaneous anaphylactic/anaphylactoid reaction, the intensity of which is proportional to the distance to which the dye diffuses into the tissue surrounding the seven sensitisation sites. Thirty minutes later, the rats are killed by CO₂ inhalation and the diameter in mm of the blue spot at each anti-serum, histamine and serotonin injection site measured. The drug dose decreasing the diameter of the blue area by 50% compared with solvent pretreated control rats (ED50), is obtained from the regression line. The dose-effect correlation is treated for statistical significance.

The DSCG-like activity, in particular histamine release inhibitor activity, can be confirmed by inhibition of histamine release in the passive peritoneal anaphylaxis test in the rat.

Rats are passively sensitised by intraperitoneal injection of 3 ml of 1:2 to 1:10 diluted rat anti-ovalbumin serum. Twenty-four hours later, the rats are treated intravenously (0.1 to 3.2 mg/kg i.v.) with the test compound. Immediately after intravenous application, the anaphylactic reaction is elicited by intravenous administration of 1 ml of 0.5% ovalbumin, immediately followed by 5 ml of HBSS (Hank's balanced salt solution) intraperitoneally. Five minutes later, the animals are decapitated and the peritoneal fluid collected and kept in an ice bath. After centrifugation for 5 minutes (350 g) at 4° C., the histamine content of the supernatant liquid is estimated fluorophotometrically (4). The effects of the test compounds are expressed as percentage changes in histamine release compared with controls.

For the above-mentioned use, the dosage will, of course, vary depending on the compound employed, mode of administration and therapy desired. However, in general, satisfactory results are obtained when administered at a daily dosage of from about 0.1 to about 20 mg/kg of animal body weight, conveniently given in divided doses 2 to 4 times a day or in sustained release form. For the larger mammal, the total daily dosage is in the range of from about 0.5 to about 100 mg, and dosage forms suitable for oral administration comprise from about 0.1 to about 50 mg of the compounds admixed with a solid or liquid pharmaceutical carrier or diluent. 

What is claimed is:
 1. A compound of the formula ##STR19## wherein R₁ is hydrogen, alkyl of 1 to 4 carbon atoms, alkenyl or alkynyl, each of 3 to 5 carbon atoms, the multiple bond of which is not adjacent to the nitrogen atom,R₂ is hydrogen, alkyl or alkoxy, each of 1 to 8 carbon atoms, hydroxyl, fluorine, chlorine, bromine, trifluoromethyl, carboxyl or --NR₄ R₅, R₃ is hydrogen, fluorine, chlorine, bromine, hydroxyl, alkyl or alkoxy, each of 1 to 8 carbon atoms, R₄ is hydrogen, alkyl of 1 to 4 carbon atoms, phenyl or --SO₂ R₆, R₅ is hydrogen or alkyl of 1 to 4 carbon atoms and R₆ is alkyl of 1 to 4 carbon atoms, phenyl or phenyl monosubstituted by alkyl or alkoxy, each of 1 to 4 carbon atoms, fluorine, chlorine or bromine,in the form of the free base or in the form of a pharmaceutically acceptable acid addition salt thereof.
 2. 1,2,3,4-Tetrahydro-5-trifluoromethyl-9H-pyrrolo[3,4-b]quinolin-9-one.
 3. 7-Chloro-1,2,3,4-tetrahydro-4-methyl-9H-pyrrolo[3,4-b]quinolin-9-one.
 4. A pharmaceutical composition for use in preventing or treating allergic conditions which comprises an anti-allergic effective amount of a compound according to claim 1 in association with a pharmaceutical carrier or diluent.
 5. A method of preventing or treating allergic conditions which comprises administering to an animal in need of such treatment an effective amount of a compound of claim
 1. 6. A compound of the formula ##STR20## wherein R₁ is hydrogen, alkyl of 1 to 4 carbon atoms, alkenyl or alkynyl, each of 3 to 5 carbon atoms, the multiple bond of which is not adjacent to the nitrogen atom,R₂ is alkyl or alkoxy, each of 1 to 8 carbon atoms, hydroxyl, fluorine, chlorine, bromine, trifluoromethyl, carboxyl or --NR₄ R₅, R₃ is hydrogen, fluorine, chlorine, bromine, hydroxyl, alkyl or alkoxy, each of 1 to 8 carbon atoms, R₄ is hydrogen, alkyl of 1 to 4 carbon atoms, phenyl or --SO₂ R₆, R₅ is hydrogen or alkyl of 1 to 4 carbon atoms, and R₆ is alkyl of 1 to 4 carbon atoms, phenyl or phenyl monosubstituted by alkyl or alkoxy, each of 1 to 4 carbon atoms, fluorine, chlorine or bromine,in the form of the free base or in the form of a pharmaceutically acceptable acid addition salt thereof.
 7. A compound of the formula ##STR21## wherein R₁ is hydrogen, alkyl of 1 to 4 carbon atoms, alkenyl or alkynyl, each 3 to 5 carbon atoms, the multiple bond of which is not adjacent to the nitrogen atom,R₂ is chlorine or trifluoromethyl, R₃ is hydrogen, fluorine, chlorine, bromine, hydroxyl, alkyl or alkoxy, each of 1 to 8 carbon atoms, in the form of the free base or in the form of a pharmaceutically acceptable acid addition salt thereof.
 8. The compound of claim 6 wherein R₁ is H, R₂ is 7-OCH₃ and R₃ is H.
 9. The compound of claim 6 wherein R₁ is CH₃, R₂ is 7-OCH₃ and R₃ is H.
 10. The compound of claim 6 wherein R₁ is H, R₂ is 5-CH₃ and R₃ is H.
 11. The compound of claim 6 wherein R₁ is H, R₂ is 5-F and R₃ is H.
 12. The compound of claim 6 wherein R₁ is H, R₂ is 7-Cl and R₃ is H.
 13. The compound of claim 6 wherein R₁ is H, R₂ is 5-CH₃ and R₃ is 7-Cl.
 14. The compound of claim 6 wherein R₁ is H, R₂ is 5-CH₃ and R₃ is 7-CH₃.
 15. The compound of claim 6 wherein R₁ is H, R₂ is 5-CH₃ and R₃ is 6-CH₃.
 16. The compound of claim 6 wherein R₁ is H, R₂ is 7-C₄ H₉ and R₃ is H.
 17. The compound of claim 6 wherein R₁ is H, R₂ is 5-C₃ H₇ O and R₃ is H.
 18. The compound of claim 6 wherein R₁ is H, R₂ is 7-C₆ H₁₃ O and R₃ is H.
 19. The compound of claim 6 wherein R₁ is H, R₂ is 5-CH₃ O and R₃ is 8-CH₃ O.
 20. The compound of claim 6 wherein R₁ is CH₂ -CH═CH₂, R₂ is 5-CH₃ and R₃ is 7-CH₃.
 21. The compound of claim 6 wherein R₁ is H, R₂ is 5-CH₃ O and R₃ is 8-CH₃.
 22. The compound of claim 6 wherein R₁ is H, R₂ is 6-CF₃ and R₃ is 7-Cl.
 23. The compound of claim 6 wherein R₁ is H, R₂ is 5-Cl and R₃ is 7-Cl.
 24. The compound of claim 6 wherein R₁ is H, R₂ is 7-(CH₃)₂ N-- and R₃ is H.
 25. The compound of claim 6 wherein R₁ is H, R₂ is 7-OH and R₃ is H.
 26. The compound of claim 6 wherein R₁ is CH₃, R₂ is 7-NH₂ and R₃ is H.
 27. The compound of claim 6 wherein R₁ is --(CH₂)₂ C.tbd.CH, R₂ is 5-C₃ H₇ and R₃ is 7-C₂ H₅.
 28. The compound of claim 6 wherein R₁ is CH₃, R₂ is 7-Br and R₃ is 5-C₂ H₅ O.
 29. The compound of claim 6 wherein R₁ is CH₃, R₂ is 5-COOH and R₃ is H.
 30. The compound of claim 6 wherein R₁ is H, R₂ is ##STR22## and R₃ is 5-CH₃.
 31. The compound of claim 6 wherein R₁ is H, R₃ is ##STR23## and R₃ is 5-CH₃ O.
 32. The compound of claim 6 wherein R₁ is CH₃, R₂ is 5-C₄ H₉ O and R₃ is 7-F.
 33. The compound of claim 6 wherein R₁ is C₂ H₅, R₂ is 5-C₇ H₁₅ and R₃ is 7-Br.
 34. The compound of claim 6 wherein R₁ is C₄ H₉, R₂ is 6-OH and R₃ is H.
 35. The compound of claim 6 wherein R₁ is H, R₂ is ##STR24## and R₃ is 5-C₃ H₇.
 36. The compound of claim 1 wherein R₁ is C₂ H₅, R₂ is H and R₃ is H. 